The present invention comprises an improvement of the subject matter of copending application Ser. No. 945,237, filed Sept. 25, 1978, and relates to a positive displacement rotary vane pump of the reversible type which automatically provides unidirectional discharge flow, regardless of direction of rotation. Reversible pumps are useful in many applications, such as for oil pumps for lubricating three-phase powered refrigeration compressors, which are run in clockwise or counterclockwise directions because the start-up of such compressors can result in rotation in either direction.
Rotary pumps adapted to provide unidirectional flow regardless of direction of rotation of the pump are known in the art. For example, U.S. patents disclosing reversible rotary vane pumps include U.S. Pat. Nos. 1,722,595 and 3,985,473. Other pumps providing unidirectional output include gear pumps, such as disclosed in U.S. Pat. Nos. 2,151,482; 3,165,066; 3,208,392; and 3,343,494. And a reversible shear pump is disclosed in U.S. Pat. No. 3,039,677.
It is an object of the present invention to provide an improved reversible, unitary flow pump, and particularly one which reliably has relatively few parts and can be economically constructed and maintained. A further object is to provide a rotary pump having improved automatic valve means comprising a single porting/valve plate for providing unidirectional output regardless of direction of rotation. A related object concerns the provision of such a pump which does not require inlet valving.
These and other objects, features and advantages of the present invention will be apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.